1. Field of Invention
The present invention relates to semiconductor devices, methods for manufacturing the same, circuit substrates and electronic devices.
2. Description of Related Art
The related art includes semiconductor devices having a stacked structure that realize high density mounting. For example, a related art configuration includes a plurality of semiconductor chips stacked one on top of the other on a die pad of a lead frame, in which the semiconductor chips are electrically connected to leads by wires. In this case, electrodes of each of the semiconductor chips are directly bonded to the leads by the wires.
However, the distance between the electrodes of the semiconductor chips and the leads is greater than the distance between the electrodes of the different semiconductor chips. Also, when the wires are routed around from the leads as starting points to each of the semiconductor chips, the entire length of the wires becomes long. For this reason, the resistance of the wires becomes greater, which has sometimes prevented enhancements toward higher speeds. Also, since the wires are long, they are therefore apt to become short-circuited with other wires.
The present invention addresses or solves the problems described above, and enhances reliability and achieves higher speeds for semiconductor devices with a stacked structure.
A semiconductor device in accordance with the present invention includes:
a die pad;
a plurality of semiconductor chips stacked on one surface of the die pad;
a lead extending toward the die pad;
a first wire that is bonded to a first pad of a first semiconductor chip among the plurality of semiconductor chips and to a second pad of a second semiconductor chip among the plurality of semiconductor chips;
a second wire that is bonded to the lead and to one of the first pad and the second pad; and
a sealing material that seals the plurality of semiconductor chips and exposes another surface of the die pad.
In accordance with the present invention, the first wire is bonded to the first pad of the first semiconductor chip and the second pad of the second semiconductor chip. In other words, the first and second semiconductor chips are directly, electrically connected to each other by the first wire. For this reason, the entire length of the wires (the length of the first and second wires combined) can be made to be shorter compared to the case where wires are lead out from the leads as starting points to the first and second pads. As a result, the material cost for the wires can be reduced, and semiconductor devices can achieve higher speeds since the entire wire resistance can be lowered. Also, since the overall wire length is short, the first and second wires are prevented or substantially prevented from becoming short-circuited.
In the semiconductor device, the second semiconductor chip may be mounted on the first semiconductor chip, and the second wire may be bonded to the lead and to the second pad.
In the semiconductor device, the second wire may be lead out to pass above the first wire.
As a result, the first and second wires are prevented or substantially prevented from becoming short-circuited.
In the semiconductor device, the second wire may be lead out to traverse the first wire.
As a result, the second wire can be routed around freely without being limited to configurations in which the first wire is routed around.
In the semiconductor device, the second wire may be overlapped with and bonded to the first wire on the second pad.
As a result, even when the second pad region is narrow, a plurality of wires can be bonded to the second pad.
In the semiconductor device, the second wire may include a ball formed on a tip thereof, and the ball may be press-bonded to the first wire.
As a result, by press-bonding the ball on the second wire to a part of the first wire on the second pad, the bonded section of the first wire and the second wire can be reinforced.
In the semiconductor device, the second wire may be bonded to the second pad that is bonded to the first wire, while avoiding a bonded section of the first wire.
As a result, for example, the first and second wires do not have to be overlapped with each other, and therefore the first and second wires can be securely bonded to the second pad.
In the semiconductor device,
the second semiconductor chip may include a plurality of the second pads,
the plurality of the second pads may include a group of pads that are electrically connected to one another by a wiring,
the first wire may be bonded to one of the group of pads, and
the second wire may be bonded to another of the group of pads.
As a result, for example, the first and second wires do not have to be overlapped with each other, and therefore the first and second wires can be securely bonded to the second pad.
In the semiconductor device,
the second pad may be provided with a bump, and
the first wire and the second wire may be bonded to the second pad through the bump.
In the semiconductor device, the second semiconductor chip may be mounted on the first semiconductor chip, and the second wire may be bonded to the lead and to the first pad.
In the semiconductor device, the first semiconductor chip may be a memory, and the second semiconductor chip may be a microprocessor.
A circuit substrate in accordance with the present invention mounts the aforementioned semiconductor device.
An electronic device in accordance with the present invention includes the aforementioned semiconductor device.
A method for manufacturing a semiconductor device in accordance with the present invention includes:
(a) stacking a plurality of semiconductor chips on one surface of a die pad;
(b) bonding a first wire to a first pad of a first semiconductor chip among the plurality of semiconductor chips and to a second pad of a second semiconductor chip among the plurality of semiconductor chips;
(c) bonding a second wire to a lead that extends toward the die pad and to one of the first pad and the second pad; and
(d) sealing the plurality of semiconductor chips and exposing another surface of the die pad.
In accordance with the present invention, the first wire is bonded to the first pad of the first semiconductor chip and the second pad of the second semiconductor chip. In other words, the first and second semiconductor chips are directly, electrically connected to each other by the first wire. For this reason, the entire length of the wires (the length of the first and second wires combined) can be made to be shorter compared to the case where wires are lead out from the leads as starting points to the first and second pads. As a result, the material cost for the wires can be reduced, and semiconductor devices can achieve higher speeds since the entire wire resistance can be lowered. Also, since the overall wire length is short, the first and second wires are prevented or substantially prevented from becoming short-circuited.
In the method for manufacturing a semiconductor device,
in step (a), the second semiconductor chip may be mounted on the first semiconductor chip, and
in step (c), the second wire may be bonded to the lead and the second pad.
In the method for manufacturing a semiconductor device,
in step (c), the second wire may be lead out to pass over the first wire.
As a result, the first and second wires are prevented or substantially prevented from becoming short-circuited.
In the method for manufacturing a semiconductor device,
in step (c), the second wire may be lead out to traverse the first wire.
As a result, the second wire can be routed around freely without being limited to configurations in which the first wire is routed around.
In the method for manufacturing a semiconductor device,
in step (c), the second wire may be overlapped with and bonded to the first wire on the second pad.
As a result, even when the second pad region is narrow, a plurality of wires can be bonded to the second pad.
In the method for manufacturing a semiconductor device,
in step (c), a ball may be formed on a tip portion of the second wire, and the ball may be press-bonded to the first wire.
As a result, by press-bonding the ball on the second wire to a part of the first wire on the second pad, the bonded section of the first wire and the second wire can be reinforced.
In the method for manufacturing a semiconductor device,
in steps (b) and (c), the first wire and the second wire may be bonded to the second pad without forming balls.
In the method for manufacturing a semiconductor device,
in step (c), the second wire may be bonded to the second pad that is bonded to the first wire, while avoiding a bonded section of the first wire.
As a result, for example, the first and second wires do not have to be overlapped with each other, and therefore the first and second wires can be securely bonded to the second pad.
In the method for manufacturing a semiconductor device, the second semiconductor chip may include a plurality of the second pads,
the plurality of the second pads may include a group of pads that are electrically connected to one another by a wiring,
in step (b), the first wire may be bonded to one of the group of pads, and
in step (c), the second wire may be bonded to another of the group of pads.
As a result, for example, the first and second wires do not have to be overlapped with each other, and therefore the first and second wires can be securely bonded to the second pad.
In the method for manufacturing a semiconductor device,
in steps (b) and (c),
the second pad may be provided with a bump, and
the first wire and the second wire may be bonded to the second pad through the bump.